Dual Xeon vs P-4?

Currently using a Dell 420 SCSI Workstation with 512MB rambus memory & single P-III processor, SCSI 10K drives...However no amount of adjusting memory or hardware configurations can turn this into a machine that can process two (2) or three (3) open graphics programs at once without crashing or just sitting there; you probably know what I mean. I use CorelDraw 10, Adobe, FrontPage & other Web designing tools plus Lt CAD. all graphics intensive programs by themselves, and some need to be open together.
I want to BUILD a system that will currently handle "Win XP Pro" plus the above mentioned programs without causing me so much grief!
There is confusion about the set-up.
Two 3+GHz Xeon processors with 2GB DDR memory on a WI-2P Abit motherboard with a 7505 chipset vs one P-4, 3.60GHz with 2GB memory on a Intel or other motherboard with an 876 chipset, dito memory! I have never build a system but keep 4 office Dells all network running so I am not intimited by the Build-Process. Any one who has first hand knowledge and has done a, from scratch build I would appreciate any input.
Thanks,
A. Vancortlandt